Polished gemstone

ABSTRACT

A gemstone, on which respectively at least four facets of equal size have been cut in the upper part and the lower part above and below the girdle plane, which have a parallel base edge, wherein the angle (α) between an upper part facet (20 . . . 23) and the girdle plane is less than the angle (β) between a lower part facet (10 . . . 13) and the girdle plane. Between the lateral edges of the lower part facets (10, 11, 12, 13) one group (40 . . . 43) of narrow, triangular additional facets, which extend fan-like from a girdle plane, is provided. The narrow sides of the one group of additional facets meet in the connecting lines between the tips of the lower part facets (10, 11, 12, 13) and the narrow sides of the additional facets of a respectively neighboring group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a gemstone on which respectively at least fourfacets of equal size have been cut in the upper part and the lower partabove and below a girdle plane, which have a parallel base edge, whereinthe angle between an upper part facet and the girdle plane is less thanthe angle between a lower part facet and the girdle plane.

2. Prior Art

Such a cut of a gemstone is known, for example, from DE-PS 15 57 625,wherein an equal number of facets on the upper part and facets on thelower part determine the appearance and its optical properties.

A comparable cut is known from DE 42 10 995 A1, wherein it is intendedthat particular angles between the facets on the upper part and facetson the lower part lead to a particularly noticeable appearance,essentially by planar effects which differ in their brightness.

A further development of these types of cuts is shown in DE 32 02 302A1, wherein outer facets include the girdle plane.

Finally, DE 27 20 267 C2 shows a diamond, which has a very complexstructure of cut surfaces, among them also narrow triangular facetswhich, combined into groups, widen in a fan shape from the area close tothe top of the diamond down to circumferential lateral facets. In itsoptical effects, the interplay of the multitude of different facets alsoleads to a complex, rather confusing appearance.

BRIEF SUMMARY OF THE INVENTION

It is the object of the invention to apply a cut which offers a novelappearance regarding brilliance and lightness effects while maintainingthe basic shape of the diamond crystal.

In accordance with the invention, this object is attained by a gemstonecomposed of an upper part and a lower part, said upper and lower partsbeing disposed at respectively opposite sides of a girdle plane,wherein:

said upper part consists of a plurality of upper part facets of equalsize, each upper part facet forming a first angle (α) with the girdleplane;

said lower part comprises a plurality of lower part facets each havingtwo lateral edges that extend away from the girdle plane and meet at atip that is remote from the girdle plane, each lower part facet forminga second angle (β) with the girdle plane, the first angle (α) being lessthan the second angle (β);

said tips of said lower part facets are spaced from one another and saidlower part is formed to have connecting lines between said tips;

said lower part further comprises a plurality of groups of narrow,triangular additional facets that fan out from the girdle plane, eachgroup being located between lateral edges of a respective pair or saidlower part facets;

each of said additional facets has a narrow side which coincides with asegment of one of the connecting lines; and

the narrow side of each additional facet of one group meets the narrowside of one additional facet of a respective neighboring group.

When observing the gemstone from the top, the fan-like extending groupof additional facets at the lower part leads to a reflection for theobserver such that, per facet surface, a rayor star-shaped light effectoccurs on the four pyramid-shaped facets of the upper part, which is incontrast to the so far known rather planar light effects in connectionwith the types of cuts mentioned at the outset.

The quadruple bundling of the light in this case leads to the appearanceof reflections, which penetrate the total surface of the diamond severaltimes.

Advantageous embodiments of the attainment of the object of theinvention ensue from the dependent claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A preferred embodiment will be explained in still more detail by meansof the drawings. Shown are in:

FIG. 1, a perspective plan view of the cut gemstone obliquely frombelow,

FIG. 2, a top view of the gemstone in the direction of the arrow A inFIG. 3,

FIG. 3, a lateral view of the gemstone in the direction of the arrow Cin FIG. 4, and

FIG. 4, a bottom view of the gemstone in the direction of the arrow B inFIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The upper portion of the gemstone, which consists of four top partfacets 20 . . . 23 of equal size, which taper to form an upper cap,rises above the square girdle plane. Here the top part facet forms anisosceles triangle. The girdle plane may also be circular.

The lower part of the diamond contains four lower part facets 10 . . .13, which also form an isosceles triangle.

The common base side of the upper part facets and lower part facets isformed by a circumferential facet band 30 perpendicularly in respect tothe girdle plane.

Four groups 40 . . . 43 of narrow, essentially triangular additionalfacets extend from the four corners of the girdle plane between thelateral edges of the lower part facets 10 . . . 13 in such a way thattheir narrow sides meet in the connecting lines between the tips oflower parts facets 10 . . . 13 with the narrow sides of the additionalfacets of the respectively neighboring group. Here each group consistsof a central additional facet, whose roof-like narrow sides form apyramid-shaped cap K of the lower part, and which, in the exemplaryembodiment represented, are adjoined by respectively four narrowtriangular additional facets on both sides. With the exemplaryembodiment represented, the central additional facet is also embodied asa narrow triangle, but it is also possible (not represented) to providethe central additional facet with parallel lateral edges, so that in itseffect it approximately corresponds to the circumferential facet band30. The planes of neighboring additional facets are inclined at a veryacute angle in respect to each other, so that in the exemplaryembodiment represented, the 36 additional facets close the gemstone atthe bottom is the shape of a cupola between the lower part facets 10 . .. 13.

Depending on the type of gemstone, the angle α between each of the upperpart facets 20 . . . 23 and the girdle plane lies between 23° and 30°,the angle β between the each of lower part facets 10 . . . 13 and thegirdle plane lies between 34° and 43°.

Each group 40-43 of additional facets is preferably formed of at leastthree additional facets whose longitudinal sides enclose an angle ofapproximately 5° to 15°. The appearance of a gemstone cut in this way isessentially determined by the cupola-like arrangement of the additionalfacets, which, because of the multitude of occurring angles ofinclination and diffraction, mirrors a lively optical image on the upperpart facets when light enters evenly from below, and is characterized byevenly arranged or distributed star-like light effects, which in theirgeometry actively reproduce the naturally provided geometry of thegemstone.

I claim:
 1. A gemstone composed of an upper part and a lower part, saidupper and lower parts being disposed at respectively opposite sides of agirdle plane, wherein:said upper part consists of a plurality of upperpart facets of equal size, each upper part facet forming a first angle(α) with the girdle plane; said lower part comprises a plurality oflower part facets each having two lateral edges that extend away fromthe girdle plane and meet at a tip that is remote from the girdle plane,each lower part facet forming a second angle (β) with the girdle plane,the first angle (α) being less than the second angle (β); said tips ofsaid lower part facets are speaded from one another and said lower partis formed to have connecting lines between said tips; said lower partfurther comprises a plurality of groups of narrow, triangular additionalfacets that fan out from the girdle plane, each group being locatedbetween lateral edges of a respective pair or said lower part facets;each of said additional facets has a narrow side which coincides with asegment of one of the connecting lines; and the narrow side of eachadditional facet of one group meets the narrow side of one additionalfacet of a respective neighboring group.
 2. The gemstone in accordancewith claim 1, characterized in that the angle (α) between each one ofthe upper part facets (20 . . . 23) and the girdle plane is 23° to 30°.3. The gemstone in accordance with claim 1, characterized in that theangle (β) between each one of the lower part facets (10 . . . 13) andthe girdle plane is 34° to 43°.
 4. The gemstone in accordance with claim1, characterized in that each group (40 . . . 43) of additional facetsis formed of at least three additional facets, each additional facethaving longitudinal sides which enclose an angle of approximately 5° to15°.
 5. The gemstone in accordance with claim 4, characterized in thateach group of additional facets includes a central additional facethaving two narrow sides, the narrow sides of said central additionalfacets form a pyramid-shaped cap of said lower part, and said centraladditional facet of each said group is adjoined at each side by at leastone other additional facet.
 6. The gemstone in accordance with claim 1,characterized in that the planes of neighboring additional facets areinclined toward each other at an angle of approximately 1° to 3°, sothat the total of at least twelve additional facets close off thegemstone in an approximately cupola-shaped manner at the bottom.
 7. Thegemstone in accordance with claim 1, characterized in that the girdleplane has a circumferential facet band (30).
 8. The gemstone inaccordance with claim 1, characterized in that the girdle plane issquare.